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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 639 · 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): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  3. 3.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  4. 4.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  5. 5.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?
  6. 6.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?
  7. 7.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?
  8. 8.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  9. 9.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  10. 10.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?
  11. 11.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  13. 13.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?
  14. 14.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  15. 15.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  17. 17.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?
  18. 18.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?
  19. 19.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  21. 21.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  22. 22.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  23. 23.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?
  24. 24.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?
  25. 25.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?
  26. 26.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  28. 28.A leapfrog list starts 9, 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 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.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?
  32. 32.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  33. 33.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?
  34. 34.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?
  35. 35.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  36. 36.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.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?
  38. 38.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  39. 39.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  40. 40.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?

Answer key

  1. 1199
  2. 660
  3. 803
  4. 473
  5. 286
  6. 198
  7. 319
  8. 858
  9. 363
  10. 418
  11. 506
  12. 946
  13. 869
  14. 198
  15. 1199
  16. 594
  17. 1023
  18. 253
  19. 880
  20. 528
  21. 902
  22. 1177
  23. 517
  24. 781
  25. 825
  26. 704
  27. 308
  28. 671
  29. 858
  30. 913
  31. 759
  32. 374
  33. 407
  34. 341
  35. 638
  36. 198
  37. 429
  38. 1144
  39. 847
  40. 231

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