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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 430 · 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): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  2. 2.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?
  3. 3.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  4. 4.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  5. 5.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  6. 6.A leapfrog list starts 5, 9 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): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  8. 8.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  9. 9.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  11. 11.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?
  12. 12.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?
  13. 13.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  14. 14.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  15. 15.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?
  16. 16.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  17. 17.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  18. 18.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  19. 19.A leapfrog list starts 8, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  21. 21.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  22. 22.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  24. 24.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  25. 25.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  26. 26.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  28. 28.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  29. 29.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  30. 30.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  31. 31.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?
  32. 32.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  33. 33.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  34. 34.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?
  35. 35.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  36. 36.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?
  37. 37.A leapfrog list starts 4, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  40. 40.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?

Answer key

  1. 748
  2. 1034
  3. 847
  4. 418
  5. 1012
  6. 1067
  7. 858
  8. 561
  9. 649
  10. 1144
  11. 495
  12. 1177
  13. 583
  14. 1089
  15. 143
  16. 649
  17. 693
  18. 1023
  19. 1056
  20. 1177
  21. 1199
  22. 715
  23. 429
  24. 924
  25. 473
  26. 902
  27. 561
  28. 803
  29. 550
  30. 671
  31. 594
  32. 605
  33. 396
  34. 418
  35. 968
  36. 363
  37. 660
  38. 561
  39. 462
  40. 759

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