A school corridor has a line of lockers. Every sixth locker has a pen, every eighth locker has an exercise book and every ninth locker has a textbook. What is the number of the first locker which has all three items? 

Simplify:

$284-(6\times 65÷13+20\times 5-40)$

Simplify the following:

$\{370÷37(45\times 5^2÷5-35+7\left)\right\}$

Simplify:

$84\times [69-\{7\times 6-(12÷3\times 8)\left\}\right]$

Simplify the following:

$(34+66 of 29)+[19-\{385÷(30÷6\times 7)\left\}\right]$

Simplify 

$[580-18 of1-\{16\times 14+(270÷9-38+68)\left\}\right]$

Write the factors of:

$36$

Write all factors of:

$81$

Write all factors of:

$275$