Dow is giving consumers a mathematical teaser with a 'giant chalkboard' painted on a brick wall at the corner of Broome and Crosby in SoHo, Manhattan.

Yesterday, 90,000 people walked by the 46ft chalkboard with only a twitter handle (@giantchalkboard) and website URL (giantchalkboard.com) to give them a clue to its meaning.

Today, the chalkboard will feature the beginning of an elaborate equation full of twists and turns that combines mathematics with numbers that are significant to scientific human achievements throughout history. The banner says 'Solutionism. The new optimism.'

The campaign, through Draftfcb Chicago, invites people to participate and guess the answers through Twitter and the website. On the fifth day, the answer will be revealed.