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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 321 · 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. 1.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  2. 2.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  4. 4.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  6. 6.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?
  7. 7.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?
  8. 8.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  9. 9.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  11. 11.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  12. 12.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?
  13. 13.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?
  14. 14.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  15. 15.A leapfrog list starts 8, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  17. 17.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?
  18. 18.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?
  19. 19.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?
  20. 20.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  21. 21.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?
  22. 22.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  24. 24.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?
  25. 25.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  26. 26.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?
  27. 27.A leapfrog list starts 9, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  29. 29.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.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?
  31. 31.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  32. 32.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?
  33. 33.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  35. 35.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  36. 36.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  37. 37.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  38. 38.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?
  39. 39.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  40. 40.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?

Answer key

  1. 1001
  2. 979
  3. 924
  4. 319
  5. 462
  6. 374
  7. 781
  8. 1122
  9. 550
  10. 638
  11. 605
  12. 451
  13. 143
  14. 957
  15. 792
  16. 880
  17. 671
  18. 770
  19. 814
  20. 363
  21. 1122
  22. 902
  23. 715
  24. 759
  25. 1034
  26. 671
  27. 1287
  28. 726
  29. 583
  30. 693
  31. 396
  32. 286
  33. 737
  34. 682
  35. 682
  36. 1089
  37. 1056
  38. 407
  39. 627
  40. 341

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