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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 100 · 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, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  2. 2.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  3. 3.A leapfrog list starts 3, 4 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 3, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  6. 6.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  7. 7.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  8. 8.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  10. 10.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?
  11. 11.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  12. 12.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  13. 13.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  14. 14.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  15. 15.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?
  16. 16.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.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?
  18. 18.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  19. 19.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  20. 20.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  21. 21.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  22. 22.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?
  23. 23.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  24. 24.A leapfrog list starts 5, 4 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): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  26. 26.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  27. 27.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.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?
  29. 29.A leapfrog list starts 3, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.9 + 9 + 18 + 27 + 45 + 72 + 117 + 189 + 306 + 495 =
  31. 31.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.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?
  33. 33.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  34. 34.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  37. 37.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  38. 38.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  39. 39.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  40. 40.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?

Answer key

  1. 1067
  2. 495
  3. 517
  4. 781
  5. 198
  6. 429
  7. 616
  8. 374
  9. 913
  10. 814
  11. 649
  12. 1111
  13. 693
  14. 759
  15. 737
  16. 451
  17. 231
  18. 968
  19. 319
  20. 1012
  21. 935
  22. 572
  23. 946
  24. 627
  25. 704
  26. 715
  27. 946
  28. 396
  29. 869
  30. 1287
  31. 418
  32. 891
  33. 869
  34. 814
  35. 1001
  36. 836
  37. 979
  38. 583
  39. 781
  40. 594

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