Mike Jacobs
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mikejacobs.bsky.social
Mike Jacobs
@mikejacobs.bsky.social
460 followers 42 following 530 posts
Math teacher in Ontario/Mountaineer/Munroist/Exiled Yorkshireman/Dad to two great kids.
Creator of Yohaku Puzzle https://www.yohaku.ca/
Author of Onwards and Upwards. https://tinyurl.com/OnwardsUpwardsHills .
#RunEveryDay
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mikejacobs.bsky.social
Here's a #yohaku to take you into the weekend. Fill in cells with 16 different factors of 540 to get totals shown in each row/column AND shaded cells contain triangle numbers. #mathsky #iTeachMath
Use 16 different factors of 540 in a 4 by 4 grid. The numbers in the top row add to 40. The numbers in the second row add to 103. The numbers in the third row add to 90. The numbers in the bottom row add to 113. The numbers in the left column add to 189. The numbers in the second column add to 61. The numbers in the third column add to 84. The numbers in the right column add to 12. The central four cells contain triangle numbers.
November 14, 2025 at 1:21 PM
mikejacobs.bsky.social
Try this shady #yohaku. Fill in cells with 9 different integers to get products shown in each row/column AND sum of 4 shaded cells is -4. #mathsky #iTeachMath
Use 9 different integers in a 3 by 3 grid. The numbers in the top row multiply to -104. The numbers in the middle row multiply to 154. The numbers in the bottom row multiply to 63. The numbers in the left column multiply to 182. The numbers in the middle column multiply to -132. The numbers in the right column multiply to 42. The sum of the integers in the 2 by 2 square at the top left of the grid is -4.
November 13, 2025 at 11:45 AM
mikejacobs.bsky.social
Start your day with this #yohaku. Fill in cells with 9 different factors of 350 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 350 in a 3 by 3 grid. The numbers in the top row add to 42. The numbers in the middle row add to 87. The numbers in the bottom row add to 76. The numbers in the left column add to 76. The numbers in the middle column add to 79. The numbers in the right column add to 50.
November 12, 2025 at 11:49 AM
mikejacobs.bsky.social
Start your day with this #yohaku. Fill in cells with 9 different whole numbers to get products shown in each row/column. More free puzzles and books/ebooks for all ages can be found at yohaku.ca
Use 9 different whole numbers in a 3 by 3 grid. The numbers in the top row multiply to 56. The numbers in the middle row multiply to 312. The numbers in the bottom row multiply to 84. The numbers in the left column multiply to 84. The numbers in the middle column multiply to 48. The numbers in the right column multiply to 364.
November 11, 2025 at 11:59 AM
mikejacobs.bsky.social
I came across a really nice way of visually showing the sum of the first n square numbers. Details in this blog:
themathguy.blogspot.com/2025/11/the-...
The Sum of the First n Square Numbers
One of the things I like to do as a teacher is provide visual proofs of why certain formulas work. A nice one that I use a lot in high scho...
themathguy.blogspot.com
November 10, 2025 at 3:57 PM
mikejacobs.bsky.social
Start your week with this #yohaku. Fill in cells with 9 different factors of 120 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 120 in a 3 by 3 grid. The numbers in the top row add to 57. The numbers in the middle row add to 85. The numbers in the bottom row add to 46. The numbers in the left column add to 10. The numbers in the middle column add to 90. The numbers in the right column add to 88.
November 10, 2025 at 11:45 AM
mikejacobs.bsky.social
Here's a #yohaku to take you into the weekend. Fill in cells with 16 different factors of 432 to get totals shown in each row/column AND shaded cells contain square numbers. #mathsky #iTeachMath
Use 16 different factors of 432 in a 4 by 4 grid. The numbers in the top row add to 14. The numbers in the second row add to 43. The numbers in the third row add to 148. The numbers in the bottom row add to 231. The numbers in the left column add to 43. The numbers in the second column add to 70. The numbers in the third column add to 177. The numbers in the right column add to 146. The central four cells contain triangle numbers.
November 7, 2025 at 11:48 AM
mikejacobs.bsky.social
Try this shady #yohaku. Fill in cells with 9 different integers to get products shown in each row/column AND sum of 4 shaded cells is -5. #mathsky #iTeachMath
Use 9 different integers in a 3 by 3 grid. The numbers in the top row multiply to -210. The numbers in the middle row multiply to -18. The numbers in the bottom row multiply to 44. The numbers in the left column multiply to -42. The numbers in the middle column multiply to 495. The numbers in the right column multiply to -8. The sum of the integers in the 2 by 2 square at the top left of the grid is -5.
November 6, 2025 at 11:51 AM
mikejacobs.bsky.social
Start your day with this #yohaku. Fill in cells with 9 different factors of 910 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 910 in a 3 by 3 grid. The numbers in the top row add to 78. The numbers in the middle row add to 84. The numbers in the bottom row add to 218. The numbers in the left column add to 197. The numbers in the middle column add to 22. The numbers in the right column add to 161.
November 5, 2025 at 11:53 AM
mikejacobs.bsky.social
"Start your day with this #yohaku. Fill in cells with 9 different whole numbers to get products shown in each row/column. More free puzzles and books/ebooks for all ages can be found at yohaku.ca
Use 9 different whole numbers in a 3 by 3 grid. The numbers in the top row multiply to 36. The numbers in the middle row multiply to 52. The numbers in the bottom row multiply to 765. The numbers in the left column multiply to 390. The numbers in the middle column multiply to 136. The numbers in the right column multiply to 27.
November 4, 2025 at 11:43 AM
mikejacobs.bsky.social
Start your week with this #yohaku. Fill in cells with 9 different factors of 294 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 294 in a 3 by 3 grid. The numbers in the top row add to 107. The numbers in the middle row add to 98. The numbers in the bottom row add to 36. The numbers in the left column add to 76. The numbers in the middle column add to 106. The numbers in the right column add to 59.
November 3, 2025 at 11:44 AM
mikejacobs.bsky.social
Don't forget to turn ALL your clocks back today!
November 2, 2025 at 7:43 PM
mikejacobs.bsky.social
Here's a #yohaku to take you into the weekend. Fill in cells with 16 different factors of 882 to get totals shown in each row/column AND shaded cells contain square numbers. #mathsky #iTeachMath
Use 16 different factors of 882 in a 4 by 4 grid. The numbers in the top row add to 210. The numbers in the second row add to 607. The numbers in the third row add to 205. The numbers in the bottom row add to 25. The numbers in the left column add to 48. The numbers in the second column add to 119. The numbers in the third column add to 506. The numbers in the right column add to 374. The central four cells contain triangle numbers.
October 31, 2025 at 10:49 AM
mikejacobs.bsky.social
Try this shady #yohaku. Fill in cells with 9 different integers to get products shown in each row/column AND sum of 4 shaded cells is -4. #mathsky #iTeachMath
Use 9 different integers in a 3 by 3 grid. The numbers in the top row multiply to 56. The numbers in the middle row multiply to -297. The numbers in the bottom row multiply to -20. The numbers in the left column multiply to 210. The numbers in the middle column multiply to 88. The numbers in the right column multiply to 18. The sum of the integers in the 2 by 2 square at the top left of the grid is -4.
October 30, 2025 at 10:48 AM
mikejacobs.bsky.social
Start your day with this #yohaku. Fill in cells with 9 different factors of 350 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 350 in a 3 by 3 grid. The numbers in the top row add to 95. The numbers in the middle row add to 85. The numbers in the bottom row add to 32. The numbers in the left column add to 82. The numbers in the middle column add to 89. The numbers in the right column add to 41.
October 29, 2025 at 10:48 AM
mikejacobs.bsky.social
Start your day with this #yohaku. Fill in cells with 9 different whole numbers to get products shown in each row/column. More free puzzles and books/ebooks for all ages can be found at yohaku.ca
#mathsky #iTeachMath
Use 9 different whole numbers in a 3 by 3 grid. The numbers in the top row multiply to 54. The numbers in the middle row multiply to 130. The numbers in the bottom row multiply to 693. The numbers in the left column multiply to 630. The numbers in the middle column multiply to 66. The numbers in the right column multiply to 117.
October 28, 2025 at 10:45 AM
mikejacobs.bsky.social
Start your week with this #yohaku. Fill in cells with 9 different factors of 140 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 140 in a 3 by 3 grid. The numbers in the top row add to 55. The numbers in the middle row add to 50. The numbers in the bottom row add to 20. The numbers in the left column add to 65. The numbers in the middle column add to 44. The numbers in the right column add to 16.
October 27, 2025 at 10:44 AM
mikejacobs.bsky.social
Here's a #yohaku to take you into the weekend. Fill in cells with 16 different factors of 432 to get totals shown in each row/column AND shaded cells contain square numbers. #mathsky #iTeachMath
Use 16 different factors of 432 in a 4 by 4 grid. The numbers in the top row add to 219. The numbers in the second row add to 71. The numbers in the third row add to 188. The numbers in the bottom row add to 12. The numbers in the left column add to 37. The numbers in the second column add to 186. The numbers in the third column add to 115. The numbers in the right column add to 152. The central four cells contain triangle numbers.
October 24, 2025 at 10:50 AM
mikejacobs.bsky.social
Try this shady #yohaku. Fill in cells with 9 different integers to get products shown in each row/column AND sum of 4 shaded cells is -2.
#mathsky #iTeachMath
Use 9 different integers in a 3 by 3 grid. The numbers in the top row multiply to -168. The numbers in the middle row multiply to -65. The numbers in the bottom row multiply to -495. The numbers in the left column multiply to 260. The numbers in the middle column multiply to -54. The numbers in the right column multiply to 385. The sum of the integers in the 2 by 2 square at the top left of the grid is -2.
October 23, 2025 at 10:53 AM
mikejacobs.bsky.social
Start your day with this #yohaku. Fill in cells with 9 different factors of 156 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 156 in a 3 by 3 grid. The numbers in the top row add to 82. The numbers in the middle row add to 29. The numbers in the bottom row add to 34. The numbers in the left column add to 40. The numbers in the middle column add to 13. The numbers in the right column add to 92.
October 22, 2025 at 11:08 AM
mikejacobs.bsky.social
"Start your day with this #yohaku. Fill in cells with 9 different whole numbers to get products shown in each row/column. More free puzzles and books/ebooks for all ages can be found at yohaku.ca
Use 9 different whole numbers in a 3 by 3 grid. The numbers in the top row multiply to 117. The numbers in the middle row multiply to 90. The numbers in the bottom row multiply to 240. The numbers in the left column multiply to 72. The numbers in the middle column multiply to 180. The numbers in the right column multiply to 195.
October 21, 2025 at 10:47 AM
mikejacobs.bsky.social
Start your week with this #yohaku. Fill in cells with 9 different factors of 210 to get totals shown in each row/column. #mathsky #iTeachMath
Use 9 different factors of 210 in a 3 by 3 grid. The numbers in the top row add to 26. The numbers in the middle row add to 118. The numbers in the bottom row add to 9. The numbers in the left column add to 120. The numbers in the middle column add to 24. The numbers in the right column add to 9.
October 20, 2025 at 12:46 PM
mikejacobs.bsky.social
Wonderful moment on my run today when I saw a family of five beavers including these two kits.
October 19, 2025 at 2:16 AM
mikejacobs.bsky.social
Here's a #yohaku to take you into the weekend. Fill in cells with 16 different factors of 700 to get totals shown in each row/column AND shaded cells contain square numbers. #mathsky #iTeachMath
Use 16 different factors of 700 in a 4 by 4 grid. The numbers in the top row add to 408. The numbers in the second row add to 206. The numbers in the third row add to 219. The numbers in the bottom row add to 28. The numbers in the left column add to 202. The numbers in the second column add to 38. The numbers in the third column add to 146. The numbers in the right column add to 475. The central four cells contain triangle numbers.
October 17, 2025 at 4:29 PM
mikejacobs.bsky.social
Try this shady #yohaku. Fill in cells with 9 different integers to get products shown in each row/column AND sum of 4 shaded cells is 3. #mathsky #iTeachMath
Use 9 different integers in a 3 by 3 grid. The numbers in the top row multiply to 28. The numbers in the middle row multiply to 27. The numbers in the bottom row multiply to -260. The numbers in the left column multiply to 84. The numbers in the middle column multiply to -90. The numbers in the right column multiply to 26. The sum of the integers in the 2 by 2 square at the top left of the grid is 3.
October 16, 2025 at 11:10 AM