SOLUTION: Darien ordered a soda for $2.75. a sandwich for $8.50, and a desert for $3.85 Sales tax was $1.15. Use mental math to find the total amount of the bill. Explain. I Don't under

Algebra ->  Distributive-associative-commutative-properties -> SOLUTION: Darien ordered a soda for $2.75. a sandwich for $8.50, and a desert for $3.85 Sales tax was $1.15. Use mental math to find the total amount of the bill. Explain. I Don't under      Log On


   

Question 1152073: Darien ordered a soda for $2.75. a sandwich for $8.50, and a desert for $3.85 Sales tax was $1.15. Use mental math to find the total amount of the bill. Explain.
I Don't understand this question it gets me confused I don't know what to do with the numbers
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
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Use mental math to find the total amount of the bill.
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Do the sum of the given items using their prices, in your head.

Can you do this without writing any steps on paper?
2.75%2B8.50%2B3.85%2B1.15


You could try this:
Look at the whole part of EACH number.
2, 8, 3, 1;
You can understand their sum: 14.

What else? Take the fraction part of each of the given numbers:
0.75, 0.50, 0.85, 0.15;
It may take a little more thinking, but can you figure the sum of these without writing anything?
0.75%2B0.5=1.25
AND
0.85%2B0.15=1.00
AND then
together, the fractions parts sum to 2.25.


And you can finish the rest.

Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


Different people are going to do this in different ways. The basic strategy is to look for ways that make the calculations easier.

Glancing quickly at the given amount, I immediately see one amount with 85 cents and another with 15 cents. Those add up to a dollar, so I am going to use that "shortcut" somehow in my calculations.

I might look just at the cents first, and then do the dollars separately. That way I would have the 85 cents plus the 15 cents giving me a dollar; then the other cents, 50 and 75, give me another $1.25, so the total of the cents is $2.25.

Then I could add up the dollars to get 2+8+3+1 = 14; so the final total is $14+$2.25 = $16.25.

Being good with mental arithmetic, I wouldn't do the cents and dollars separately. I would start with the $3.85 plus $1.15 giving me $5; then the other two added together give me $11.25, making the final total $16.25.