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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 940 · 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): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  4. 4.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  6. 6.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?
  7. 7.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?
  8. 8.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  9. 9.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?
  10. 10.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?
  11. 11.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  12. 12.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?
  13. 13.A leapfrog list starts 9, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.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?
  16. 16.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  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. 18.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  20. 20.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  21. 21.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?
  22. 22.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  23. 23.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?
  24. 24.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  25. 25.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  27. 27.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  28. 28.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  29. 29.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?
  30. 30.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?
  31. 31.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  32. 32.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  34. 34.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  35. 35.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  36. 36.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  37. 37.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  38. 38.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?
  39. 39.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  40. 40.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?

Answer key

  1. 451
  2. 814
  3. 836
  4. 605
  5. 143
  6. 418
  7. 803
  8. 1012
  9. 649
  10. 649
  11. 1199
  12. 1122
  13. 1111
  14. 253
  15. 847
  16. 616
  17. 704
  18. 957
  19. 891
  20. 1089
  21. 902
  22. 1023
  23. 715
  24. 198
  25. 935
  26. 1067
  27. 726
  28. 781
  29. 308
  30. 946
  31. 594
  32. 748
  33. 231
  34. 583
  35. 946
  36. 286
  37. 770
  38. 198
  39. 704
  40. 473

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