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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 589 · 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): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  2. 2.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?
  3. 3.A leapfrog list starts 7, 9 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): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  6. 6.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  7. 7.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?
  8. 8.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?
  9. 9.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?
  10. 10.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  11. 11.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  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. 13.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  14. 14.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?
  15. 15.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?
  16. 16.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?
  17. 17.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?
  18. 18.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?
  19. 19.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  20. 20.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?
  21. 21.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  23. 23.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  24. 24.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?
  25. 25.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  27. 27.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?
  28. 28.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?
  29. 29.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  31. 31.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  32. 32.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  33. 33.A leapfrog list starts 3, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  35. 35.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  37. 37.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?
  38. 38.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  39. 39.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?
  40. 40.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?

Answer key

  1. 1122
  2. 957
  3. 1177
  4. 781
  5. 715
  6. 231
  7. 726
  8. 253
  9. 286
  10. 759
  11. 539
  12. 726
  13. 143
  14. 484
  15. 891
  16. 1023
  17. 198
  18. 638
  19. 649
  20. 671
  21. 759
  22. 880
  23. 517
  24. 814
  25. 803
  26. 825
  27. 462
  28. 858
  29. 1089
  30. 1056
  31. 484
  32. 319
  33. 957
  34. 198
  35. 891
  36. 396
  37. 1287
  38. 473
  39. 825
  40. 1001

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