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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 980 · 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. 1.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  2. 2.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  3. 3.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  4. 4.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  6. 6.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  7. 7.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?
  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. 9.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  10. 10.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  11. 11.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  12. 12.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?
  13. 13.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  14. 14.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  15. 15.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  16. 16.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?
  17. 17.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  18. 18.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?
  19. 19.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?
  20. 20.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?
  21. 21.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?
  22. 22.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  23. 23.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  25. 25.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?
  26. 26.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  27. 27.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  28. 28.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  29. 29.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  30. 30.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  31. 31.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  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. 33.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  34. 34.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.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?
  36. 36.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?
  37. 37.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?
  38. 38.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?
  39. 39.Leapfrog list (each number is the sum of the two before it): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  40. 40.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =

Answer key

  1. 781
  2. 1067
  3. 363
  4. 143
  5. 418
  6. 902
  7. 957
  8. 253
  9. 231
  10. 902
  11. 539
  12. 957
  13. 847
  14. 429
  15. 847
  16. 616
  17. 847
  18. 231
  19. 913
  20. 880
  21. 429
  22. 803
  23. 253
  24. 1287
  25. 1287
  26. 495
  27. 583
  28. 627
  29. 946
  30. 286
  31. 1111
  32. 1177
  33. 737
  34. 1001
  35. 528
  36. 671
  37. 891
  38. 770
  39. 748
  40. 1067

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