Say 'I Love You' to your mathematician Valentine, mathematically. The first and third mathematical expression equal i and u respectively. The equation is the heart shape graph. Together it stands for "i love u", which is printed on the inside of the card (with the heart shape in place of the word love). If you would like to add your own messages with the same colors as the existing ones, select colour code hex 660000 (under the Customize it option, in the color selection table, check the color on the 2nd row from the bottom, 5th color from the right, and verify the color code number).