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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 998 · 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. 2.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  3. 3.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  7. 7.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?
  8. 8.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  9. 9.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  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.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?
  12. 12.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?
  13. 13.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  14. 14.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  15. 15.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  16. 16.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  18. 18.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  19. 19.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  21. 21.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  22. 22.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  23. 23.A leapfrog list starts 5, 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): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  25. 25.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  26. 26.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?
  27. 27.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  28. 28.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  29. 29.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?
  30. 30.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  31. 31.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  32. 32.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  33. 33.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  35. 35.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  36. 36.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  37. 37.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?
  38. 38.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?
  39. 39.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  40. 40.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 550
  2. 693
  3. 638
  4. 1199
  5. 1023
  6. 759
  7. 968
  8. 803
  9. 726
  10. 583
  11. 583
  12. 143
  13. 1177
  14. 231
  15. 924
  16. 1034
  17. 847
  18. 396
  19. 627
  20. 759
  21. 1012
  22. 1144
  23. 363
  24. 814
  25. 1287
  26. 572
  27. 418
  28. 539
  29. 891
  30. 253
  31. 847
  32. 869
  33. 495
  34. 957
  35. 1001
  36. 858
  37. 1012
  38. 1023
  39. 143
  40. 1034

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