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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 617 · 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): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  2. 2.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  3. 3.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?
  4. 4.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?
  5. 5.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  6. 6.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  8. 8.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.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?
  10. 10.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  11. 11.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  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. 13.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  14. 14.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  15. 15.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?
  16. 16.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  17. 17.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  18. 18.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  20. 20.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  21. 21.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?
  22. 22.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?
  23. 23.A leapfrog list starts 8, 9 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): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  25. 25.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?
  26. 26.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  27. 27.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?
  28. 28.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?
  29. 29.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  31. 31.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?
  32. 32.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?
  33. 33.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?
  34. 34.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  35. 35.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  36. 36.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  38. 38.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?
  39. 39.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  40. 40.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =

Answer key

  1. 363
  2. 748
  3. 495
  4. 1111
  5. 605
  6. 1177
  7. 902
  8. 759
  9. 528
  10. 308
  11. 1001
  12. 671
  13. 429
  14. 319
  15. 1089
  16. 462
  17. 528
  18. 638
  19. 869
  20. 803
  21. 528
  22. 715
  23. 1232
  24. 605
  25. 143
  26. 550
  27. 759
  28. 638
  29. 1012
  30. 1111
  31. 737
  32. 253
  33. 1023
  34. 847
  35. 913
  36. 726
  37. 561
  38. 649
  39. 1199
  40. 1232

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