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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 688 · 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.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  3. 3.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  4. 4.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?
  5. 5.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  8. 8.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?
  9. 9.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?
  10. 10.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  12. 12.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  13. 13.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  14. 14.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  15. 15.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?
  16. 16.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  18. 18.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  19. 19.A leapfrog list starts 3, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  21. 21.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  22. 22.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?
  23. 23.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  24. 24.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  25. 25.A leapfrog list starts 7, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  27. 27.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  28. 28.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?
  29. 29.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  31. 31.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  32. 32.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?
  33. 33.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?
  34. 34.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  35. 35.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  36. 36.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  37. 37.A leapfrog list starts 3, 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 1, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?

Answer key

  1. 583
  2. 473
  3. 1001
  4. 286
  5. 671
  6. 759
  7. 902
  8. 671
  9. 825
  10. 286
  11. 935
  12. 627
  13. 418
  14. 1034
  15. 462
  16. 803
  17. 649
  18. 759
  19. 869
  20. 946
  21. 1001
  22. 484
  23. 506
  24. 869
  25. 737
  26. 803
  27. 671
  28. 198
  29. 759
  30. 341
  31. 231
  32. 308
  33. 1056
  34. 847
  35. 583
  36. 462
  37. 605
  38. 671
  39. 1177
  40. 627

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