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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 609 · 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): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  4. 4.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  6. 6.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  7. 7.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?
  8. 8.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?
  9. 9.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?
  10. 10.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?
  11. 11.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.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?
  13. 13.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?
  14. 14.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  15. 15.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  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.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  18. 18.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  19. 19.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  20. 20.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  21. 21.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?
  22. 22.A leapfrog list starts 2, 5 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): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  24. 24.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  26. 26.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  28. 28.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?
  29. 29.A leapfrog list starts 1, 1 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 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  32. 32.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  33. 33.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  34. 34.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.A leapfrog list starts 7, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.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?
  37. 37.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  38. 38.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?
  39. 39.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  40. 40.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?

Answer key

  1. 1089
  2. 1023
  3. 968
  4. 759
  5. 374
  6. 638
  7. 814
  8. 935
  9. 528
  10. 253
  11. 847
  12. 671
  13. 286
  14. 737
  15. 506
  16. 715
  17. 913
  18. 539
  19. 803
  20. 1001
  21. 616
  22. 550
  23. 825
  24. 473
  25. 935
  26. 649
  27. 286
  28. 1023
  29. 143
  30. 528
  31. 143
  32. 572
  33. 1067
  34. 451
  35. 737
  36. 781
  37. 143
  38. 231
  39. 682
  40. 704

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