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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 616 · 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.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  5. 5.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  6. 6.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  7. 7.A leapfrog list starts 4, 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 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  9. 9.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?
  10. 10.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  12. 12.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?
  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. 14.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  15. 15.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  16. 16.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?
  17. 17.A leapfrog list starts 8, 9 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): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  19. 19.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?
  20. 20.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?
  21. 21.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?
  22. 22.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?
  23. 23.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  27. 27.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  28. 28.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?
  29. 29.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  30. 30.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  31. 31.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?
  32. 32.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?
  33. 33.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?
  34. 34.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?
  35. 35.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  36. 36.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  37. 37.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?
  38. 38.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  40. 40.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =

Answer key

  1. 550
  2. 649
  3. 473
  4. 253
  5. 902
  6. 319
  7. 836
  8. 594
  9. 715
  10. 847
  11. 979
  12. 638
  13. 143
  14. 649
  15. 726
  16. 726
  17. 1232
  18. 539
  19. 451
  20. 759
  21. 319
  22. 231
  23. 891
  24. 737
  25. 902
  26. 649
  27. 847
  28. 825
  29. 792
  30. 759
  31. 1034
  32. 715
  33. 759
  34. 726
  35. 308
  36. 891
  37. 792
  38. 847
  39. 1111
  40. 660

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