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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 358 · 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 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  3. 3.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  4. 4.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  5. 5.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  7. 7.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?
  8. 8.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  9. 9.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  10. 10.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  11. 11.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  12. 12.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  13. 13.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?
  14. 14.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?
  15. 15.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  16. 16.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  17. 17.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?
  18. 18.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  20. 20.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?
  21. 21.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?
  22. 22.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?
  23. 23.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  24. 24.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?
  25. 25.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  26. 26.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?
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  29. 29.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  30. 30.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  31. 31.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  33. 33.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?
  34. 34.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  35. 35.A leapfrog list starts 7, 5 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 4, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  38. 38.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  39. 39.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?
  40. 40.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =

Answer key

  1. 528
  2. 1122
  3. 891
  4. 1177
  5. 715
  6. 572
  7. 231
  8. 1023
  9. 704
  10. 1023
  11. 814
  12. 528
  13. 693
  14. 1067
  15. 528
  16. 1287
  17. 308
  18. 1056
  19. 902
  20. 913
  21. 660
  22. 1012
  23. 1144
  24. 759
  25. 726
  26. 484
  27. 726
  28. 671
  29. 1199
  30. 473
  31. 572
  32. 462
  33. 803
  34. 902
  35. 825
  36. 1012
  37. 341
  38. 286
  39. 462
  40. 770

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