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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 721 · 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. 1.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  2. 2.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  3. 3.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?
  4. 4.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?
  5. 5.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  6. 6.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  7. 7.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?
  8. 8.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?
  9. 9.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?
  10. 10.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  11. 11.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  12. 12.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  13. 13.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?
  14. 14.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  15. 15.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  16. 16.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?
  17. 17.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  18. 18.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  19. 19.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  20. 20.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  21. 21.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  22. 22.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  23. 23.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?
  24. 24.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  25. 25.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.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?
  28. 28.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  29. 29.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  30. 30.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?
  31. 31.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  33. 33.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  34. 34.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  35. 35.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  37. 37.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?
  38. 38.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 715
  2. 1232
  3. 902
  4. 770
  5. 1001
  6. 913
  7. 1089
  8. 407
  9. 1056
  10. 979
  11. 418
  12. 429
  13. 319
  14. 605
  15. 979
  16. 638
  17. 704
  18. 484
  19. 748
  20. 814
  21. 1144
  22. 583
  23. 462
  24. 308
  25. 726
  26. 1122
  27. 374
  28. 759
  29. 561
  30. 506
  31. 880
  32. 825
  33. 880
  34. 957
  35. 671
  36. 880
  37. 748
  38. 968
  39. 671
  40. 286

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