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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 219 · 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. 1.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  2. 2.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?
  3. 3.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  4. 4.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  6. 6.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?
  7. 7.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  8. 8.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  10. 10.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?
  11. 11.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  12. 12.A leapfrog list starts 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  14. 14.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  15. 15.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  16. 16.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  17. 17.A leapfrog list starts 4, 7 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 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  20. 20.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  21. 21.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?
  22. 22.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?
  23. 23.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  25. 25.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  26. 26.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  27. 27.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  28. 28.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  29. 29.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?
  30. 30.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  31. 31.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?
  32. 32.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.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?
  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. 36.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  37. 37.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  38. 38.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  40. 40.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =

Answer key

  1. 968
  2. 583
  3. 726
  4. 1034
  5. 1089
  6. 638
  7. 1034
  8. 891
  9. 968
  10. 506
  11. 396
  12. 484
  13. 341
  14. 473
  15. 418
  16. 649
  17. 836
  18. 1144
  19. 627
  20. 308
  21. 561
  22. 671
  23. 759
  24. 671
  25. 704
  26. 517
  27. 902
  28. 715
  29. 561
  30. 1287
  31. 649
  32. 1089
  33. 539
  34. 946
  35. 572
  36. 594
  37. 682
  38. 759
  39. 374
  40. 792

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