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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 23 · 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, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 4, 9 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): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  4. 4.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  5. 5.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  6. 6.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  7. 7.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?
  8. 8.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?
  9. 9.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  10. 10.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  11. 11.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?
  12. 12.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.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?
  14. 14.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  15. 15.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  17. 17.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?
  18. 18.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  19. 19.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  21. 21.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?
  22. 22.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?
  23. 23.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?
  24. 24.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?
  25. 25.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?
  26. 26.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?
  27. 27.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  28. 28.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  29. 29.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?
  30. 30.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  32. 32.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?
  33. 33.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  34. 34.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  35. 35.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?
  36. 36.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  37. 37.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  38. 38.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  39. 39.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  40. 40.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =

Answer key

  1. 715
  2. 1012
  3. 605
  4. 847
  5. 715
  6. 946
  7. 869
  8. 473
  9. 572
  10. 671
  11. 1177
  12. 286
  13. 1111
  14. 462
  15. 803
  16. 693
  17. 748
  18. 814
  19. 341
  20. 583
  21. 1089
  22. 451
  23. 726
  24. 759
  25. 726
  26. 616
  27. 891
  28. 286
  29. 913
  30. 407
  31. 836
  32. 143
  33. 1023
  34. 583
  35. 231
  36. 561
  37. 319
  38. 836
  39. 968
  40. 781

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