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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 647 · 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): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
  4. 4.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?
  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. 6.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  7. 7.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?
  8. 8.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  9. 9.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  10. 10.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?
  11. 11.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  12. 12.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  13. 13.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  14. 14.A leapfrog list starts 3, 2 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 1, 9 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): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  17. 17.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  18. 18.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?
  19. 19.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  20. 20.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  21. 21.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  23. 23.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?
  24. 24.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?
  25. 25.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  26. 26.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  27. 27.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?
  28. 28.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  29. 29.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  30. 30.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  31. 31.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  32. 32.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  33. 33.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  34. 34.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?
  35. 35.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?
  36. 36.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  37. 37.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  38. 38.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  40. 40.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?

Answer key

  1. 979
  2. 1122
  3. 770
  4. 737
  5. 649
  6. 902
  7. 539
  8. 803
  9. 1067
  10. 407
  11. 407
  12. 605
  13. 1067
  14. 341
  15. 847
  16. 407
  17. 363
  18. 759
  19. 583
  20. 341
  21. 286
  22. 308
  23. 704
  24. 968
  25. 594
  26. 539
  27. 374
  28. 671
  29. 1199
  30. 1144
  31. 506
  32. 660
  33. 308
  34. 649
  35. 418
  36. 913
  37. 704
  38. 693
  39. 836
  40. 583

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