Question

Write down the first 10 numbers that can be arranged as Triangle.

Answer 1

Numbers that can be written in the form of Triangles are:

First number is $1$

Second number is $1+2=3$

Third number is $3+3=6$

Fourth number is $6+4=10$

Fifth number is $10+5=15$

Sixth number is $15+6=21$

Seventh number is $21+7=28$

Eighth number is $28+8=36$

Ninth number is $36+9=45$

Tenth number is $45+10=55$

Hence, Triangle numbers follow the above pattern.