Let's work with either fractions or decimals, but not with both at the same time. We'll start with decimals. 1 1/4 inches is 1.25 inches (divide 4 into 1.00 to convert 1/4 to decimal: 1.00/4=0.25). Multiply 1.25 by 7.25=9.0625 sq in. To multiply the decimals you can use long multiplication to multiply 125 by 725, and put the decimal point in later. Where does it go? Count the number of digits following the decimal point for each number and add the counts together. Each has 2 digits after the decimal point and 2+2=4, so the decimal point goes in four digits from the end and 90625 becomes 9.0625.
Let's work with fractions. We've seen that 0.25 is 1/4 so 7.25=7 1/4. To multiply two fractions together convert them to improper fractions: 1 1/4 is 5/4 (4 times the integer 1 plus the numerator 1 is 5 and divide by the fraction denominator); 7.25 is 7 1/4=29/4 (4 times 7 plus 1=29 divided by 4). Now multiply 5/4*29/4=145/16=9 1/16 sq in.