Using only p&p(no calculator), determine the value of:
95+94+93+92+9
In analogy with 10^5+10^4+10^3+10^2+10
= ((10^5-1)/9)*10:
9^5+9^4+9^3+9^2+9
= ((9^5-1)/8)*9
as it represents a repunit times the base in base-9 rather than base ten.
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Posted by Charlie
on 2024-10-07 09:38:05 |