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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 438 · 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.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  5. 5.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  6. 6.A leapfrog list starts 3, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  8. 8.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  9. 9.A leapfrog list starts 5, 3 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 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  13. 13.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  14. 14.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?
  15. 15.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?
  16. 16.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  17. 17.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  19. 19.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?
  20. 20.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  21. 21.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?
  22. 22.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  23. 23.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  24. 24.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  26. 26.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  27. 27.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  28. 28.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  29. 29.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  30. 30.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  31. 31.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  33. 33.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  35. 35.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?
  36. 36.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  37. 37.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  38. 38.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  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. 550
  2. 396
  3. 660
  4. 924
  5. 561
  6. 781
  7. 451
  8. 517
  9. 539
  10. 583
  11. 748
  12. 583
  13. 583
  14. 847
  15. 759
  16. 1144
  17. 968
  18. 594
  19. 902
  20. 957
  21. 198
  22. 231
  23. 539
  24. 726
  25. 693
  26. 506
  27. 649
  28. 561
  29. 781
  30. 759
  31. 1111
  32. 715
  33. 957
  34. 1122
  35. 462
  36. 1012
  37. 671
  38. 759
  39. 616
  40. 418

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