Doubles are adding the same number together, as with 5+5=10.
With doubles +1, the numbers must be in beside each other in counting order going up or down (ex: 4, 5, 6 and 9, 8, 7). Do the SMALLEST number, double it, then add one. So, 9+8 would be 8+8=16, +1=17. You must know your doubles facts before this strategy is useful.
Answer: 
Step-by-step explanation:
Let us first represent the ratio.
3
Now we need to convert 3
into a improper fraction.
Now it is in its simplest form.
The final answer is
I don't need to know anything about all that rounding stuff.
You said that there are 3 digits, they are all the same, and their sum is 15.
So each of them must be ( 15 / 3 ) = 5 .
The number is <em>555</em> .
Rounded to the nearest ten pence
If the one place is 5 and above, round up
If the one place is less than 5, then round down.
So
T shirts 453.56 = 450
Hoodies 679.84 = 680
Bottle openers 550.45 = 550
Key rings 22.21 = 20
Posters 86.45 = 90
Books 14.99 = 10
The correct answer is 3.45x10^5
