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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 513 · 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 8, 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): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  3. 3.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?
  4. 4.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  5. 5.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  7. 7.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?
  8. 8.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?
  9. 9.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  10. 10.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?
  11. 11.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?
  12. 12.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?
  13. 13.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  14. 14.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.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?
  16. 16.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  17. 17.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?
  18. 18.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  19. 19.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  21. 21.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  22. 22.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?
  23. 23.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  24. 24.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?
  25. 25.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  26. 26.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?
  27. 27.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. 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 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  30. 30.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  31. 31.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.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?
  33. 33.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  34. 34.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?
  35. 35.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  36. 36.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  37. 37.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?
  38. 38.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?
  39. 39.A leapfrog list starts 1, 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): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?

Answer key

  1. 704
  2. 616
  3. 286
  4. 473
  5. 550
  6. 1023
  7. 374
  8. 792
  9. 363
  10. 583
  11. 1023
  12. 1122
  13. 1232
  14. 1177
  15. 913
  16. 143
  17. 671
  18. 396
  19. 1199
  20. 957
  21. 759
  22. 253
  23. 726
  24. 462
  25. 869
  26. 836
  27. 902
  28. 198
  29. 935
  30. 649
  31. 429
  32. 374
  33. 308
  34. 726
  35. 891
  36. 704
  37. 484
  38. 638
  39. 407
  40. 319

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