Question 1089427

suman is {{{7}}} years {{{younger}}} to his brother {{{aman}}}

 {{{suman=aman -7}}}

 diameter of a circle is twice the radius:
{{{ diameter=2*radius}}} or short {{{d=2r}}}

 successor of a natural number {{{n}}}:{{{n+ 1}}}

by definition: 
Every natural number has a unique successor.
0 is not the successor of a natural number.
Different natural numbers have different successors.
The successor of a natural number {{{n}}} is {{{n+ 1}}}.