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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 501 · 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, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  2. 2.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  3. 3.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  4. 4.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?
  5. 5.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  6. 6.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?
  7. 7.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  8. 8.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?
  9. 9.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?
  10. 10.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  11. 11.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?
  12. 12.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  13. 13.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  14. 14.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?
  15. 15.A leapfrog list starts 9, 7 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): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  17. 17.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  18. 18.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  19. 19.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  20. 20.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?
  21. 21.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  22. 22.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?
  23. 23.A leapfrog list starts 2, 6 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 2, 9 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 8, 2 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): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  27. 27.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  28. 28.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?
  29. 29.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  30. 30.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  31. 31.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  32. 32.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  33. 33.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  34. 34.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  35. 35.A leapfrog list starts 4, 4 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 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.A leapfrog list starts 4, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  40. 40.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 319
  2. 1232
  3. 539
  4. 407
  5. 1067
  6. 605
  7. 429
  8. 1089
  9. 902
  10. 1001
  11. 649
  12. 946
  13. 561
  14. 143
  15. 1111
  16. 1023
  17. 1144
  18. 814
  19. 803
  20. 759
  21. 957
  22. 506
  23. 638
  24. 902
  25. 616
  26. 198
  27. 759
  28. 891
  29. 891
  30. 902
  31. 781
  32. 550
  33. 924
  34. 825
  35. 572
  36. 561
  37. 660
  38. 726
  39. 583
  40. 473

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