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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 570 · 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, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  2. 2.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  3. 3.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  5. 5.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  6. 6.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  7. 7.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?
  8. 8.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  9. 9.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?
  10. 10.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  11. 11.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 7, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  14. 14.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  15. 15.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  16. 16.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  18. 18.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?
  19. 19.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.Leapfrog list (each number is the sum of the two before it): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  21. 21.A leapfrog list starts 3, 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): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  23. 23.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  26. 26.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  29. 29.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  30. 30.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  31. 31.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  32. 32.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  33. 33.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  34. 34.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  35. 35.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  36. 36.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  38. 38.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?
  39. 39.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.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?

Answer key

  1. 495
  2. 1111
  3. 1144
  4. 583
  5. 1232
  6. 583
  7. 363
  8. 891
  9. 253
  10. 1199
  11. 627
  12. 825
  13. 968
  14. 473
  15. 913
  16. 286
  17. 924
  18. 198
  19. 308
  20. 748
  21. 429
  22. 528
  23. 946
  24. 517
  25. 913
  26. 715
  27. 1111
  28. 1034
  29. 319
  30. 1023
  31. 572
  32. 418
  33. 550
  34. 143
  35. 638
  36. 1023
  37. 902
  38. 583
  39. 770
  40. 825

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