Friday is Pi Day, a national celebration of the mathematical concept, which is the ratio of a circle's circumference to its diameter and equals 3.14... Schools and museums often plan events to celebrate the concept, which has fascinated humans for centuries, and local eateries offer pie-related deals.

For two days only, on March 13 and 14, CPK Rewards members can get an Original BBQ Chicken, Pepperoni, or Traditional Cheese pizza for $3.14 with any purchase of $25 or more. Non-members can enroll in CPK Rewards on CPK.com or on the CPK app anytime through March 14 to get the deal, which is available for dine-in, takeout or delivery.

March Madness pizza deals are also available. Until march 16, the Crowd Pleaser Combo is available for $24.99 with code FEED5. Here is what is included: Throughout March Madness, customers spending $7.99 or more can add menu items for $5, $6, or $7 each using code MOREMENU.