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 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
- 2.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?
- 3.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
- 4.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
- 5.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?
- 6.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 7.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
- 8.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
- 9.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
- 10.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
- 11.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
- 12.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?
- 13.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
- 14.Leapfrog list (each number is the sum of the two before it): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
- 15.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?
- 16.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
- 17.Leapfrog list (each number is the sum of the two before it): 8, 4, 12, 16, 28, 44, 72, 116, 188, 304. What is 11 × the 7th number?
- 18.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
- 19.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?
- 20.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 21.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
- 22.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?
- 23.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?
- 24.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 25.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
- 26.A leapfrog list starts 7, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 27.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?
- 28.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
- 29.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?
- 30.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?
- 31.A leapfrog list starts 7, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 32.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
- 33.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
- 34.A leapfrog list starts 7, 7 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 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 36.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
- 37.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
- 38.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 39.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
- 40.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?
Answer key
- 715
- 231
- 638
- 495
- 407
- 814
- 913
- 726
- 462
- 946
- 396
- 462
- 1232
- 616
- 1056
- 572
- 792
- 924
- 605
- 198
- 1144
- 616
- 561
- 429
- 649
- 825
- 253
- 627
- 726
- 286
- 737
- 979
- 319
- 1001
- 693
- 1001
- 1199
- 1144
- 781
- 759
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