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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 440 · 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): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  2. 2.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  3. 3.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  4. 4.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  5. 5.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  6. 6.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  7. 7.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  9. 9.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  10. 10.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?
  11. 11.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  12. 12.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?
  13. 13.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?
  14. 14.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?
  15. 15.A leapfrog list starts 3, 6 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. 17.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  18. 18.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?
  19. 19.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  20. 20.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?
  21. 21.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  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.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  27. 27.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?
  28. 28.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  29. 29.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?
  30. 30.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?
  31. 31.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?
  32. 32.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  33. 33.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?
  34. 34.Leapfrog list (each number is the sum of the two before it): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  35. 35.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?
  36. 36.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  37. 37.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  38. 38.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?
  39. 39.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?

Answer key

  1. 495
  2. 1067
  3. 363
  4. 770
  5. 880
  6. 517
  7. 1056
  8. 781
  9. 671
  10. 462
  11. 616
  12. 792
  13. 231
  14. 671
  15. 693
  16. 715
  17. 781
  18. 649
  19. 374
  20. 407
  21. 869
  22. 902
  23. 946
  24. 407
  25. 770
  26. 880
  27. 825
  28. 638
  29. 638
  30. 484
  31. 495
  32. 1177
  33. 671
  34. 616
  35. 759
  36. 396
  37. 759
  38. 693
  39. 451
  40. 319

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