Answer:
996,250,626,076
Explanation:
You want the value of the numerical expression 251^5+8-(9×20+3).
Calculator
Your calculator will evaluate this properly if you enter it as shown. See the attachment.
If you're doing this in parts, the Order of Operations tells you to start with the parentheses, then do the exponentiation.
251^5 +8 -(9·20 +3)
= 251^5 +8 -183
= 996,250,626,251 +8 -183 = 996,250,626,076
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Additional comment
You can use a spreadsheet (or an on-line calculator) if your calculator only displays 10 digits.