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
- 1.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
- 2.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
- 3.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?
- 4.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 5.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
- 6.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?
- 7.A leapfrog list starts 1, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 8.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
- 9.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
- 10.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?
- 11.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
- 12.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
- 13.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?
- 14.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?
- 15.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
- 16.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
- 17.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
- 18.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
- 19.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
- 20.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?
- 21.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 22.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
- 23.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?
- 24.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
- 25.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
- 26.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?
- 27.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
- 28.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
- 29.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
- 30.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
- 31.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
- 32.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
- 33.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
- 34.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 35.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?
- 36.A leapfrog list starts 4, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 37.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
- 38.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
- 39.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 40.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
Answer key
- 726
- 583
- 1232
- 847
- 968
- 715
- 671
- 143
- 418
- 935
- 638
- 946
- 473
- 462
- 308
- 1287
- 924
- 627
- 891
- 319
- 308
- 858
- 847
- 407
- 1067
- 363
- 693
- 770
- 616
- 495
- 1089
- 847
- 396
- 583
- 583
- 836
- 880
- 638
- 407
- 528
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