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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 369 · 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. 1.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  2. 2.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  3. 3.A leapfrog list starts 3, 2 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 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  6. 6.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  7. 7.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  8. 8.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?
  9. 9.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  10. 10.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?
  11. 11.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  13. 13.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?
  14. 14.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  15. 15.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?
  16. 16.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?
  17. 17.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  18. 18.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  19. 19.A leapfrog list starts 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  21. 21.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  22. 22.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.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?
  24. 24.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?
  25. 25.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  26. 26.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  27. 27.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  28. 28.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?
  29. 29.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  30. 30.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  31. 31.A leapfrog list starts 8, 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): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
  33. 33.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  34. 34.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?
  35. 35.A leapfrog list starts 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  37. 37.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  38. 38.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  39. 39.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  40. 40.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?

Answer key

  1. 506
  2. 1023
  3. 341
  4. 946
  5. 649
  6. 847
  7. 693
  8. 759
  9. 143
  10. 231
  11. 935
  12. 979
  13. 814
  14. 583
  15. 671
  16. 715
  17. 451
  18. 825
  19. 495
  20. 374
  21. 594
  22. 462
  23. 814
  24. 198
  25. 539
  26. 1056
  27. 484
  28. 1056
  29. 671
  30. 528
  31. 528
  32. 792
  33. 1144
  34. 638
  35. 605
  36. 462
  37. 748
  38. 308
  39. 198
  40. 539

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