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.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?
- 4.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
- 5.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 6.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
- 7.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
- 8.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
- 9.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
- 10.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
- 11.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 12.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?
- 13.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?
- 14.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?
- 15.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
- 16.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
- 17.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
- 18.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?
- 19.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 20.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 21.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
- 22.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 23.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
- 24.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 25.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
- 26.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?
- 27.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
- 28.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
- 29.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?
- 30.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
- 31.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?
- 32.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?
- 33.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
- 34.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
- 35.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
- 36.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?
- 37.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?
- 38.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
- 39.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
- 40.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
Answer key
- 715
- 231
- 1177
- 374
- 891
- 143
- 308
- 1144
- 660
- 616
- 902
- 748
- 660
- 495
- 748
- 682
- 594
- 286
- 627
- 594
- 1089
- 671
- 1056
- 462
- 814
- 473
- 902
- 957
- 759
- 495
- 550
- 143
- 1111
- 792
- 539
- 671
- 979
- 561
- 583
- 803
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