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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 409 · 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): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  2. 2.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?
  3. 3.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?
  4. 4.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?
  5. 5.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  6. 6.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  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.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.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?
  10. 10.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?
  11. 11.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  12. 12.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?
  13. 13.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  15. 15.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?
  16. 16.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?
  17. 17.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?
  18. 18.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?
  19. 19.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  20. 20.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  21. 21.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?
  22. 22.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  23. 23.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  24. 24.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  25. 25.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?
  26. 26.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?
  27. 27.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?
  28. 28.A leapfrog list starts 6, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.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?
  30. 30.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  32. 32.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  33. 33.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  34. 34.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  35. 35.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?
  36. 36.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?
  37. 37.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  38. 38.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  39. 39.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?
  40. 40.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =

Answer key

  1. 528
  2. 891
  3. 726
  4. 671
  5. 869
  6. 1144
  7. 836
  8. 781
  9. 1287
  10. 627
  11. 836
  12. 308
  13. 704
  14. 407
  15. 616
  16. 231
  17. 418
  18. 605
  19. 781
  20. 495
  21. 1067
  22. 231
  23. 462
  24. 858
  25. 792
  26. 748
  27. 891
  28. 770
  29. 429
  30. 968
  31. 605
  32. 1089
  33. 1001
  34. 847
  35. 671
  36. 715
  37. 825
  38. 880
  39. 880
  40. 319

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