How can Joe Root reach a 50 international batting average?

England Test captain Joe Root was left stranded at a 49.99 international batting average after scoring 66 against Pakistan at Headingley. With 22,899 runs from 458 dismissals, Root needs just one unbeaten run in the second innings to reach 22,900 runs and a 50 average. However, if dismissed, he must score at least 51 runs to offset the additional dismissal.