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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 600 · 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.A leapfrog list starts 1, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.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?
  3. 3.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  4. 4.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?
  5. 5.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  6. 6.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?
  7. 7.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  8. 8.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  10. 10.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  11. 11.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?
  12. 12.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  13. 13.A leapfrog list starts 5, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  15. 15.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  16. 16.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?
  17. 17.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  21. 21.A leapfrog list starts 9, 3 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): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  23. 23.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
  25. 25.A leapfrog list starts 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  27. 27.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  29. 29.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  30. 30.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?
  31. 31.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  32. 32.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  33. 33.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?
  34. 34.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?
  35. 35.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  37. 37.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  38. 38.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?
  39. 39.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  40. 40.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =

Answer key

  1. 143
  2. 1111
  3. 550
  4. 715
  5. 869
  6. 1001
  7. 407
  8. 814
  9. 1111
  10. 319
  11. 814
  12. 286
  13. 363
  14. 418
  15. 649
  16. 704
  17. 253
  18. 847
  19. 198
  20. 1056
  21. 759
  22. 605
  23. 935
  24. 770
  25. 374
  26. 759
  27. 869
  28. 825
  29. 748
  30. 198
  31. 374
  32. 902
  33. 550
  34. 528
  35. 704
  36. 858
  37. 1199
  38. 627
  39. 759
  40. 858

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