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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 211 · 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. 1.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  2. 2.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?
  3. 3.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  4. 4.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?
  5. 5.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?
  6. 6.A leapfrog list starts 3, 5 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 4, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  10. 10.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  11. 11.A leapfrog list starts 4, 3 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 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  14. 14.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  15. 15.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?
  16. 16.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  18. 18.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  19. 19.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?
  20. 20.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  21. 21.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  22. 22.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?
  23. 23.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  24. 24.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.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?
  26. 26.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?
  27. 27.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  28. 28.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?
  29. 29.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?
  30. 30.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  32. 32.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?
  33. 33.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  34. 34.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?
  35. 35.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  38. 38.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  39. 39.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?
  40. 40.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =

Answer key

  1. 1144
  2. 143
  3. 1023
  4. 803
  5. 946
  6. 605
  7. 836
  8. 1034
  9. 671
  10. 484
  11. 484
  12. 847
  13. 1122
  14. 418
  15. 517
  16. 473
  17. 737
  18. 836
  19. 759
  20. 616
  21. 583
  22. 418
  23. 1111
  24. 231
  25. 198
  26. 704
  27. 319
  28. 308
  29. 484
  30. 198
  31. 682
  32. 462
  33. 407
  34. 814
  35. 528
  36. 473
  37. 935
  38. 660
  39. 1199
  40. 143

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