Solve the Division Equation: Finding the Number in ?÷70=1

To solve this problem, we'll apply the properties of division:

• Step 1: Start with the given equation:
  $x:70=1$.
• Step 2: Recognize that in order to achieve the result of 1 from a division, the number being divided must be equal to the divisor.
• Step 3: Use the property of division, which states that dividing any number by itself results in 1.
  Hence, if $x \div 70 = 1$, then $x = 70$.

Therefore, the solution to the equation is 70, meaning the missing number in the equation $?:70=1$ is $x = 70$.