# Doubling and Halving When Buying T-Shirts

By Ike Prudente

During the Philippine Science High School’s ANAC I (A National Alumni Convention I) where I represented Pisay Dos (Batch ’70)  I saw a booth selling Pisay T-Shirts. I was attracted to a nice red colored shirt. So I thought of buying one for myself. But then, I thought of my 5 children who are all Pisay alumni, Rose (class of 1990), Toto (class of 1992), Tata (class of 1995), Lelay (class of 1997) and Nica (class of 1999). I selected 5 more to fit their sizes. Oh, I almost forgot Toto’s wife Rheea, who is his batchmate. And so I chose another shirt for her.

When I asked the ladies manning the booth (who are both Pisay alumni) the cost of a shirt, they told me that it is P350.

“Wow, mahal pala! Baka wala akong dalang perang pambayad” I thought.

As one of the ladies took her calculator, I blurted out “4900 divided by two is 2450.” They were amazed that when she punched in 350 x 7 in her calculator, she got 2450.

“How did you do that?” she asked me.

“I doubled P350 to get  7 hundred which when you multiply by 7 will give you 49 hundred. Now dividing this by two will give you P2450.”

By mastering doubling and halving, I expanded my multiplication tables.