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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 130 · 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 7, 3 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): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  3. 3.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  4. 4.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  6. 6.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  7. 7.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  8. 8.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?
  9. 9.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  10. 10.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?
  11. 11.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?
  12. 12.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  13. 13.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  15. 15.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  17. 17.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  18. 18.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  20. 20.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  21. 21.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  22. 22.A leapfrog list starts 9, 4 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 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.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?
  25. 25.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  26. 26.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  27. 27.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?
  28. 28.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  30. 30.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?
  31. 31.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  32. 32.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  33. 33.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  34. 34.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?
  35. 35.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  36. 36.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  37. 37.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?
  38. 38.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 649
  2. 462
  3. 1177
  4. 979
  5. 1287
  6. 792
  7. 627
  8. 935
  9. 1001
  10. 374
  11. 341
  12. 418
  13. 704
  14. 649
  15. 286
  16. 1122
  17. 616
  18. 319
  19. 1034
  20. 638
  21. 231
  22. 847
  23. 814
  24. 1232
  25. 429
  26. 1034
  27. 1111
  28. 913
  29. 198
  30. 253
  31. 1199
  32. 836
  33. 363
  34. 308
  35. 506
  36. 374
  37. 979
  38. 1023
  39. 517
  40. 803

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