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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 989 · 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. 1.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  2. 2.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  4. 4.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  5. 5.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?
  6. 6.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  7. 7.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  8. 8.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  9. 9.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  10. 10.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  11. 11.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?
  12. 12.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?
  13. 13.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?
  14. 14.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  15. 15.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  16. 16.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  17. 17.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.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?
  19. 19.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  20. 20.A leapfrog list starts 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.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?
  22. 22.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  23. 23.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  24. 24.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  26. 26.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  27. 27.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?
  28. 28.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  29. 29.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?
  30. 30.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  31. 31.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  32. 32.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  33. 33.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  35. 35.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  36. 36.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  37. 37.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  38. 38.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  39. 39.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  40. 40.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 946
  2. 462
  3. 396
  4. 594
  5. 429
  6. 539
  7. 792
  8. 616
  9. 671
  10. 649
  11. 286
  12. 649
  13. 418
  14. 781
  15. 968
  16. 308
  17. 616
  18. 715
  19. 682
  20. 396
  21. 319
  22. 605
  23. 869
  24. 638
  25. 539
  26. 1067
  27. 594
  28. 462
  29. 231
  30. 1089
  31. 847
  32. 726
  33. 473
  34. 506
  35. 572
  36. 935
  37. 638
  38. 1122
  39. 583
  40. 341

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