225

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Number

$225$ (two hundred and twenty-five) is:

$2^2 \times 3^2$

The $2$nd power of $15$ after $(1)$, $15$:

$225 = 15^2$

The sum of the first $5$ cubes:

$225 = 1^3 + 2^3 + 3^3 + 4^3 + 5^3$

The $9$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $96$, $133$, $176$:

$225 = 1 + 7 + 13 + 19 + 25 + 31 + 37 + 43 + 49 = 9 \paren {3 \times 9 - 2}$

The $12$th square after $1$, $4$, $9$, $16$, $25$, $36$, $49$, $64$, $81$, $121$, $144$ which has no more than $2$ distinct digits and does not end in $0$:

$225 = 15^2$

The $15$th square number after $1$, $4$, $9$, $16$, $25$, $36$, $49$, $64$, $81$, $100$, $121$, $144$, $169$, $196$:

$225 = 15 \times 15$

The $25$th powerful number after $1$, $4$, $8$, $9$, $16$, $25$, $\ldots$, $108$, $121$, $125$, $128$, $144$, $169$, $196$, $200$, $216$

Also see

• Previous  ... Next: Sequence of Powers of 15
• Previous  ... Next: Sum of Sequence of Cubes
• Previous  ... Next: Squares with No More than 2 Distinct Digits
• Previous  ... Next: Octagonal Number
• Previous  ... Next: Square Number
• Previous  ... Next: Powerful Number