find the wrong term in the given series
63,28,215,511
Hello,
Well, there are many possibilities...
- the numbers are odd, so 28 is the wrong term
- the numbers are in an increasing order, so 28 is the wrong term
- the sum of the numbers is <10, so 28 is the wrong term
- the one I prefer : they are all multiples of 7, so 215 is the wrong term
And another one :
- I don't know what term to choose, and I don't want to bother, so $\displaystyle \emptyset$ is the wrong term
Hello, hena!
Think cubes . . . $\displaystyle 4^3 = 64,\quad 6^3 = 216,\quad 8^3 = 512$Find the wrong term in the given sequence: 63, 28, 215, 511
We have: .$\displaystyle \begin{array}{cccc}
63 & 28 & 215 & 511 \\
\downarrow & \downarrow & \downarrow & \downarrow \\
4^3-1 & \quad{\color{red}?}\quad & 6^3-1 & 8^3-1 \end{array}$
The terms are of the form: $\displaystyle n^3-1$
. . except 28, which is $\displaystyle 3^3 {\color{red}+} 1$ . . . and is in the wrong position.