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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 932 · 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.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  2. 2.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  3. 3.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  5. 5.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  6. 6.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?
  7. 7.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  8. 8.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  11. 11.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  13. 13.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  15. 15.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  17. 17.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?
  18. 18.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  21. 21.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  23. 23.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  24. 24.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.A leapfrog list starts 9, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  27. 27.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  28. 28.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  29. 29.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  31. 31.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  33. 33.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  35. 35.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  36. 36.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  38. 38.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  39. 39.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?
  40. 40.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 231
  2. 583
  3. 198
  4. 528
  5. 671
  6. 671
  7. 803
  8. 1089
  9. 715
  10. 308
  11. 319
  12. 462
  13. 946
  14. 627
  15. 1023
  16. 319
  17. 451
  18. 1177
  19. 198
  20. 341
  21. 583
  22. 594
  23. 693
  24. 319
  25. 1111
  26. 561
  27. 550
  28. 1177
  29. 572
  30. 704
  31. 396
  32. 583
  33. 594
  34. 924
  35. 143
  36. 407
  37. 495
  38. 946
  39. 506
  40. 968

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