Leapfrog Sum Trick Worksheet
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
- 1.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
- 2.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 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?
- 4.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
- 5.A leapfrog list starts 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 6.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
- 7.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
- 8.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
- 9.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 10.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
- 11.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?
- 12.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
- 13.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?
- 14.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?
- 15.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
- 16.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 17.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
- 18.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
- 19.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
- 20.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
- 21.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
- 22.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 23.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
- 24.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
- 25.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?
- 26.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?
- 27.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
- 28.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
- 29.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 30.Leapfrog list (each number is the sum of the two before it): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
- 31.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?
- 32.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
- 33.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?
- 34.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?
- 35.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
- 36.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
- 37.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
- 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?
- 39.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
- 40.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
Answer key
- 451
- 418
- 726
- 902
- 374
- 1056
- 1034
- 1089
- 583
- 572
- 231
- 539
- 770
- 506
- 1232
- 748
- 924
- 594
- 1122
- 308
- 473
- 693
- 803
- 341
- 143
- 847
- 506
- 286
- 979
- 517
- 528
- 583
- 660
- 1111
- 1012
- 781
- 649
- 726
- 616
- 935
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