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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 947 · 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 2, 9 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): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  3. 3.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?
  4. 4.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?
  5. 5.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  6. 6.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  8. 8.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  9. 9.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  10. 10.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?
  11. 11.A leapfrog list starts 9, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  13. 13.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?
  14. 14.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  15. 15.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  16. 16.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?
  17. 17.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  18. 18.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  20. 20.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  21. 21.A leapfrog list starts 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.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?
  23. 23.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  25. 25.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?
  26. 26.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  29. 29.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?
  30. 30.Leapfrog list (each number is the sum of the two before it): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  31. 31.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  32. 32.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  33. 33.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  35. 35.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  36. 36.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  38. 38.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  39. 39.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  40. 40.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =

Answer key

  1. 902
  2. 1023
  3. 946
  4. 198
  5. 253
  6. 517
  7. 1199
  8. 814
  9. 341
  10. 253
  11. 1287
  12. 451
  13. 627
  14. 429
  15. 616
  16. 561
  17. 583
  18. 253
  19. 1177
  20. 704
  21. 858
  22. 308
  23. 847
  24. 946
  25. 704
  26. 880
  27. 1056
  28. 286
  29. 759
  30. 726
  31. 1067
  32. 1012
  33. 451
  34. 1056
  35. 506
  36. 583
  37. 198
  38. 902
  39. 319
  40. 528

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