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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 745 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  2. 2.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  4. 4.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  5. 5.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  7. 7.A leapfrog list starts 1, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  10. 10.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  12. 12.A leapfrog list starts 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  14. 14.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  15. 15.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  16. 16.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  18. 18.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  20. 20.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  21. 21.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  24. 24.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  25. 25.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  26. 26.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  28. 28.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  29. 29.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  30. 30.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  33. 33.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  34. 34.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  35. 35.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.Leapfrog list (each number is the sum of the two before it): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  38. 38.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  40. 40.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =

Answer key

  1. 869
  2. 231
  3. 880
  4. 759
  5. 1001
  6. 605
  7. 671
  8. 759
  9. 451
  10. 583
  11. 550
  12. 484
  13. 671
  14. 462
  15. 902
  16. 594
  17. 671
  18. 880
  19. 682
  20. 825
  21. 704
  22. 528
  23. 1144
  24. 253
  25. 1001
  26. 1012
  27. 814
  28. 748
  29. 506
  30. 891
  31. 957
  32. 1012
  33. 1199
  34. 363
  35. 748
  36. 506
  37. 957
  38. 418
  39. 1034
  40. 770

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