Find the total numbers to make A=21

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In summary, to find the total numbers to make A=21, you can use basic algebraic equations and solve for the unknown variables. There are multiple combinations of numbers that can add up to 21, including whole numbers and negative numbers. The order in which the numbers are added does not matter, as long as the sum is 21. Decimals cannot be used to make A=21, as the instructions specify to find "total numbers," which typically refers to whole numbers.
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Albert1
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$A=$$\square$1 $\square$2 $\square$3$\square$4 $\square$5$\square$6 $\square$7 $\square$8 $\square$9
randomly fill in each blank with eather $"+"$ or $"-"$ ,
(1) prove $A$ can not be $12$
(2) find the total numbers to make $A=21$
 
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  • #2
Albert said:
$A=$$\square$1 $\square$2 $\square$3$\square$4 $\square$5$\square$6 $\square$7 $\square$8 $\square$9
randomly fill in each blank with eather $"+"$ or $"-"$ ,
(1) prove $A$ can not be $12$
(2) find the total numbers to make $A=21$
If there is + before each number we have sum of numbers = 45
when we convert a + to a - say before n we subtract the value by 2n, hence the number shall remain odd
so $A$ cannot be 12.
we need to make the result 21 so subtract 24 so we need to choose numbers whose sum is 12 and change plus to -
the numbers are (9,3), (9,2,1), (8,4), (8,3,1), (7,5) , (7,4,1), (7,3,2), (6,5,1), (6,4,2),(6,3,2,1), (5,4,3) (5,4,2,1) that is 12 combinations.
 

FAQ: Find the total numbers to make A=21

1. How do I find the total numbers to make A=21?

To find the total numbers to make A=21, you can use basic algebraic equations and solve for the unknown variables. In this case, you would need to find two numbers that add up to 21.

2. What are the possible number combinations to make A=21?

There are multiple combinations of numbers that can add up to 21. Some examples include 10+11, 8+13, or 5+16. The possibilities are endless!

3. Can I use decimals to make A=21?

No, the instructions specify to find "total numbers," which typically refers to whole numbers. Decimals are not whole numbers, so they cannot be used to make A=21.

4. Is there a specific order in which the numbers should be added to make A=21?

No, there is no specific order in which the numbers should be added. As long as the sum of the numbers is 21, the order does not matter.

5. Can negative numbers be used to make A=21?

Yes, negative numbers can be used to make A=21. For example, -5 + 26 = 21. As long as the sum is 21, any combination of numbers can be used.

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