About Soroban Expertise I have a systematic and orderly way to organize the facts in a word problem, which (usually) leads clearly to the necessary equation. I think I can help with all types of word problems.
Experience 38 years of teaching college-level math, mostly at a two-year college.
Education/Credentials BS and MS in mathematics, SUNY Albany
Question My son received a math problem that I could not figure. There are 7 different train cars. How many combinations can you make that would be pulled by the the engine train? There must be some kind of formula to solve this equation at a 3rd grade level. Thank you- Carlos
Answer Hello, Carlos!
This is quite tricky for 3rd grade.
There are 7 different cars.
Call them: A, B, C, D, E, F, G if you like.
I'll assume we want to make 7-car combinations for the train
and the order of the cars makes difference.
For example: ABCDEFG is considered different from BCDEFGA
For the first car, we have 7 choices (any of the 7 cars).
Once we pick the first car, there are 6 choices for the second car.
Then there are 5 choices for the third car.
And 4 choices for the fourth car.
Then 3 choices for the fifth car.
And 2 choices for the sixth car.
And there's 1 car left for the seventh car.
The number of combinations is the PRODUCT of these choices.
There are: 7 × 6 × 5 × 4 × 3 × 2 × 1 = 5,040 different combinations.
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