Keep track of the cost of things that you purchase at the store before you get to the cashier. Add the cost of items together and keep a running tally of your overall costs. When you get the receipt for your goods, compare your mental math with the actual cost of what you purchased. For instance, if your cereal costs $3.99 and soap costs $9.49, your total cost would be $13.48. Wait until your tank is almost empty, then multiply the cost of gas by your tank size. For instance, if you had a 12-gallon tank, and gas was $3.50 you could multiply 12x$3.50 = $42. You can also cover up the cost of the gas on the pump while looking at the gallons and use mental math to calculate your total cost. You can use multiplication to figure out costs if you're buying more than one of the same item. For instance, if you bought 4 candy bars for 2 dollars each, you'd have 4x$2.00 = $8.00. Round the cost of the product to the nearest dollar, and calculate the percentage of the sale. For instance, if there was a 7% discount on a $9.65 item, you could round up to $10. 7% of 10 is 0.7 or 70 cents, which is approximately how much you'd save.  Ten percent off of $9.65 is actually 0.97 cents. If you are buying a case of water that costs $5 and it's 25% off, your savings would be $1.25. If you need to split a bill, you can divide the bill by the number of people who have to pay to determine how much each person owes. For instance, if you had a heating bill that cost $125.36 and you have 3 roommates, you'd divide $125.36 by 4 to get $31.34.  If you wanted to break down the equation to make it easier, work on the dollar amounts first, then the cents. Breakdown $125 to $100 to make it easier to divide by 4 or $100/4=25. Then divide $25/4 to get the remaining numbers that you're missing. Add the remainder or $6 to $25 to get the whole number of $31.
استعمل مسائل الجمع والطرح البسيطة لحساب فاتورتك بالتقريب. استعمل الضرب لحساب سعر الوقود. استغل الخصومات والعروض لتتدرب على حساب النسب المئوية. استعمل القسمة الذهنية لتقسيم الفاتورة.