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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 766 · 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 3, 5 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): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  3. 3.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?
  4. 4.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  5. 5.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  6. 6.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?
  7. 7.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  8. 8.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  10. 10.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?
  11. 11.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  12. 12.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?
  13. 13.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  15. 15.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  16. 16.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?
  17. 17.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  18. 18.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?
  19. 19.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?
  20. 20.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?
  21. 21.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  22. 22.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.A leapfrog list starts 1, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  25. 25.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  26. 26.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  27. 27.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?
  28. 28.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  29. 29.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  31. 31.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?
  32. 32.A leapfrog list starts 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  35. 35.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?
  36. 36.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  37. 37.A leapfrog list starts 1, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  39. 39.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  40. 40.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =

Answer key

  1. 605
  2. 891
  3. 198
  4. 748
  5. 143
  6. 847
  7. 341
  8. 671
  9. 1089
  10. 583
  11. 1056
  12. 726
  13. 1089
  14. 1001
  15. 1199
  16. 561
  17. 869
  18. 484
  19. 1199
  20. 968
  21. 561
  22. 506
  23. 143
  24. 451
  25. 605
  26. 781
  27. 286
  28. 253
  29. 979
  30. 550
  31. 660
  32. 858
  33. 253
  34. 649
  35. 1144
  36. 792
  37. 671
  38. 880
  39. 913
  40. 1111

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