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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 812 · 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, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  4. 4.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  5. 5.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?
  6. 6.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  7. 7.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  8. 8.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?
  9. 9.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.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?
  11. 11.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?
  12. 12.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.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?
  14. 14.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?
  15. 15.A leapfrog list starts 4, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  17. 17.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?
  18. 18.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  20. 20.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  21. 21.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  22. 22.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  23. 23.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?
  24. 24.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  26. 26.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  27. 27.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?
  28. 28.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?
  29. 29.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?
  30. 30.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  31. 31.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  32. 32.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  33. 33.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?
  34. 34.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  36. 36.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  37. 37.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  38. 38.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?
  39. 39.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?

Answer key

  1. 913
  2. 638
  3. 759
  4. 462
  5. 649
  6. 583
  7. 1034
  8. 946
  9. 1232
  10. 286
  11. 814
  12. 770
  13. 726
  14. 418
  15. 1012
  16. 627
  17. 374
  18. 1144
  19. 759
  20. 1144
  21. 528
  22. 649
  23. 1177
  24. 1199
  25. 759
  26. 902
  27. 869
  28. 1056
  29. 253
  30. 286
  31. 616
  32. 968
  33. 1122
  34. 616
  35. 858
  36. 1199
  37. 1089
  38. 704
  39. 693
  40. 418

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